TO AVOID ACCIDENT ON 2002 CHEV BLAZER 4WD. I WAS IN 2WD I HIT THE BRAKES. NOTHING HAPPENED. I PUSHED BRAKE PEDAL AS FAR AS IT WOULD GO. SEAT BELTS DID NOT TIGHTEN, I DOWNSHIFTED BUT NOTHING HAPPENED. I HEARD TWO CLUNKS IN THE REAR END. I WAS UNABLE TO SLOW DOWN FROM MY SPEED AT 30 MPH. I SAW A WARNING LIGHT ON THE DASH DURING THIS INCIDENT. I HIT A PICKUP TRUCK WHO STOPPED SUDDENLY TO AVOID A SENIOR CITIZEN WHO CROSSED LANES OF TRAFFIC IN A 65 MPH SHE WAS DOING ABOUT 30 MPH. I WAS UNABLE TO REACH EMERGANCY BRAKE IN TIME. MY WIFE REC'D TWO BROKEN RIBS AND THREE CRACKED RIBS AND BRUISING. PICKUP TRUCK HAD MINOR DAMAGE. I HAD $6,700.00 DAMAGE. I HAD JUST RECENTLY HAD A COMMAND MODULE PUT IN THE VEHICLE TO REPAIR FAULTY 4WD PROBLEM NOT GOING IN AND OUT OF 4WD WITHOUT PLAYING AROUND WITH CONTROLS. MY ABS FLAT OUT DID NOT WORK OR SLOW ME DOWN. I COULD NOT DOWNSHIFT. MY TACHOMETER WAS AT IDLE WHEN I DOWNSHIFTED.